High-speed web feed escapement mechanism



April 7, 1970 w. J. ZENNER 3,564,558

HIGH-SPEED WEB FEED ESCAPEMENT MECHANISM Filed March 21, 1968 2 Sheets-Sheet 1 Inventor Walter J. Zenner Mn pm April 7, 1970 w. J. ZENNER 3,504,558

HIGH-SPEED WEB FEED ESCAPEMENT MECHANISM Filed March 21, 1968 2 Sheets-Sheet 2 I 29 31v mi 27 I H & A 2/ 2s A 45 4s iURREIlIl H d9. 0- f 4 TIME Ira/enter 'fi wca'terizenner' g TIM? United States Patent 3,504,558 HIGH-SPEED WEB FEED ESCAPEMENT MECHANISM Walter J. Zenner, Des Plaines, lll., assignor to Extel Corporation, Chicago, 111., a corporation of Delaware Filed Mar. 21, 1968, Ser. No. 715,063 Int. Cl. F16h 27/04 US. Cl. 74143 8 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION In conventional high-speed escapement mechanisms used in telegraph recorders and other business machines, two arresting pawls are employed and two release actions are required for each cycle of operation. In such systems, in each cycle of operation the first pawl is initially released from engagement with the ratchet wheel and the second pawl is simultaneously moved toward engagement with the wheel. The ratchet wheel rotates a first incremental distance, until it engages the second pawl. The second pawl is then disengaged from the ratchet wheel and the first pawl is simultaneously moved back into blocking position. This allows the ratchet wheel to advance a further incremental distance and complete the full cycle of operation. Thus, the tape or other web is required to pause during the course of its advancing movement in each cycle.

For optimum performance at high speeds it is highly desirable to combine the two pawls in a common rigid structure. With conventional escapements, this imposes a limitation on pawl engagement to something less than fifty percent of the depth of the teeth on the ratchet wheel. For high speed operation it is also desirable to minimize the size of the ratchet wheel; accordingly, the amount of tooth engagement may become a limiting critical condition. If the ratchet wheel is made too small, there may be excessive loading of the teeth during operation with consequent early failure of the escapement mechanism.

In some particular applications, it may be desirable to provide a reversible escapement mechanism to permit the feeding of a business machine tape, or other web, at high speeds, in opposed directions. The requirement for operation of this kind may occur, for example, where certain machine instructions are to be performed on a repetitive basis or where detection of an error may require re-reading of data recorded on the tape. Conventional high-speed escapement mechanisms, in which both pawls serve to arrest rotation of the ratchet wheel, are not usually capable of reverse-direction operation.

3,504,558 Patented Apr. 7, 1970 It is an object of the present invention to provide a new and improved high-speed web feeding device, for telegraph recorders, business machines, and similar applications, which advances a paper tape or similar web on a step-by-step basis at higher speeds than have heretofore been attainable.

Another object of the invention is to provide a highspeed tape feed mechanism, controlled by a single pawl member, which advances a paper tape or like web in precisely controlled increments with the web movement constituting a continuous motion as the escapement goes through a full cycle of operation.

A further object of the invention is to provide a new and improved precision high-speed web feeding device for telegraph recorders, business machines, and similar applications which incorporates an escapement mechanism that is quickly and easily reversible in its direction of rotation to permit reversal of the direction of web feed.

Another object of the invention is to provide a highspeed precision web feeding device for telegraph recorders, business machines, and similar applications which is simple and durable in construction, which requires no critical adjustments, and which is capable of continuous reliable operation.

A high speed web-feeding device for rapidly advancing a paper tape or similar web by precisely controlled increments, constructed in accordance with the present invention, comprises a rotary web-feed member including a ratchet wheel having a plurality of ratchet teeth around its circumference. Power means are provided for urging the rotary member toward rotation in a given direction. A single pawl member is included in the device, this pawl member having first :and second pawl arms alternately engageable with circ'umferentially spaced teeth on the ratchet wheel. In the preferred construction, each pawl arm has one tooth-engaging surface oriented to block movement of the ratchet wheel in one direction and another tooth-engaging surface oriented to receive a driving impulse from one of the ratchet wheel teeth, as the rotary member rotates, to drive the pawl arm out of engagement with the wheel and to move the other pawl arm back into engagement with the wheel. The device further includes actuating means for momentarily actuating the pawl member tomove a first pawl arm out of engagement with the wheel and to move the second pawl arm toward engagement with the wheel, initiating a web feeding movement by permitting rotation of the Web feed member in the direction in which it is urged by the power means. The power means can be made reversible to permit reversible operation of the web feeding device.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by ways of illustration, show preferred embodiments of the present invention and the principles thereof and what is now considered to be the best mode contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be made as desired by those skilled in the art without departing from the present invention.

3 DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view, partly in cross section, of a high-speed web feeding device constructed in accordance with one embodiment of the present invention;

FIG. 2 is a sectional elevation view taken approximately along line 22 in FIG. 1 and showing the web-feed member of the device in an arrested position;

FIG. 3 is a sectional elevation view similar to FIG. 2 but showing the ratchet wheel of the device released for rotation;

FIG. 4 illustrates the electrical actuating signals required for reversible operation of the device of FIGS. 13;and

FIG. 5 is a sectional elevation view, similar to FIG. 3, of a further embodiment of the invention particularly constructed for reversible operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment of the invention illustrated in FIGS. 1-3, the high-speed web feeding device includes a base 11 having a first standard 12 extending upwardly and supporting a driving electrical motor 13. The output shaft 14 of motor 13 carries a firmly attached collar 15 which contains a hole for anchoring one end of a spring 16. A second upwardly etending standard 17 on base 11 supports a fixed shaft 18 that is axially aligned with motor shaft 14. A sleeve 19 is loosely fitted on shaft 18 for rotation thereon. Sleeve 19 carries a feed roll 20 and a ratchet wheel 21, both being firmly attached to the sleeve. Sleeve 19, roll 20, and ratchet wheel 21 conjointly constitute a rotary web-feed member 40. A hole in the feed roll 20 provides an anchor point for the second end of spring 16. A strip of paper tape or other web 22 to be fed engages the upper surface of feed roll 20, against which the Web is held by a pressure roll 23. Pressure roll 23 is carried by a spring biased arm 24 which holds the pressure roll in position and presses it downwardly against web 22 and feed roll 20.

A pawl member 25 is pivotally mounted on a post 27 attached to upright 17. Pawl 25 has a first pawl arm 26 which engages ratchet wheel 21 alternately with arm 26 but in a manner which does not arrest counterclockwise motion of the ratchet wheel 21. A spring 29 biases pawl member 25 in a direction to maintain blocking engagement between pawl arm 26 and ratchet wheel 21.

An electromagnet 31 is mounted to base 11 and is fitted with a pivotally mounted armature 32. The moving end of armature 32 engages a lever that is an integral part of pawl member 25. A stop member 33 limits the upward motion of armature 32.

In the operation of the high-speed tape feeding device 10, motor 13 is normally maintained energized and magnet 31 is normally not energized.

Motor 13 rotates in the direction shown by arrow C in FIG. 1, and winds spring 16 counterclockwise (arrow A, FIG. 2) until the resistance offered by spring 16 causes the motor to stall. If spring 16 subsequently becomes partially unwound, the motor again rotates to restore the spring to the fully wound condition. Because of its small size, it is practical to stall motor 13 with power or without damage to the motor.

Spring 16, at its other end, engages feed Wheel 20. Thus, motor 13 and spring 16 constitute a power means continuously exerting a rotational force on the web-feed member comprising feed wheel 20 and ratchet wheel 21, tending to rotate the web-feed member in a counterclockwise direction (arrow A).

With magnet armature 32 in the released position hown in FIG. 2, pawl member 25 is held by spring 29 with pawl arm 26 in engagement with ratchet wheel 21, blocking the ratchet wheel and feed wheel 20 from rotating. The tooth-engaging surface 41 of pawl arm 26 is specifically oriented to block counterclockwise rotation of ratchet wheel 21.

When it is desired to advance web 22 one step, a short electrical current impulse is sent through the winding of magnet 31, from an external source, not shown. This causes armature 32 to move to its attracted position as shown in FIG. 3. In its movement the armature 32 strikes lever 30 of pawl member 25 and causes pawl member 25 to rotate through a small angle. Pawl arm 26 moves out of engagement with ratchet wheel 21 and the alternate pawl arm 28 moves into engagement with the ratchet wheel.

Upon being released by pawl arm 26, ratchet wheel 21 immediately starts to rotate, driven :by spring 16. The motion of the ratchet wheel 21 drives pawl arm 28 out of engagement and moves pawl arm 26 back toward engagement with the ratchet wheel. The surface 42 of pawl arm 28 that is engaged by the ratchet wheel tooth, as the ratchet wheel rotates counterclockwise, is specifically oriented to receive a driving impulse from the ratchet wheel tooth tending to drive pawl arm 28 out of engagement with the ratchet wheel. Spring 29 aids this action and finally holds pawl arm 25 in its arresting position. As it rotates, pawl arm 25 drives magnet armature 32 to its released position against stop 33. A very short operating impulse is applied to magnet 31, so that the attracting force is no longer present when armature 32 starts its return movement toward its normal released position.

It will be seen that a short trigger pulse or signal thrctugh magnet 31 releases a flow of power from the driving motor 13 and spring 16 to rotate the Web feed member 40. The relation between ratchet wheel 21 and pawl arm 28 is such that the driving force from motor 13 and spring 16 also operates to restore the escapement pawl 25 and magnet armature 32 to their normal released positions.

Motor 13 provides an abundant source of mechanical power; however, the inertia of the motor armature makes it virtually impossible to rotate the motor shaft in the short fast steps required for precision, high-speed, incremental advance of web 22. It is the function of spring 16 to transmit the motor torque to the feed wheel 20 and also, since the inertia of spring 16 is very small, to de-couple feed wheel 20 from the inertia of motor 13.

In FIG. 2 the escapement 10 is shown in its arrested state and in FIG. 3 it is shown released for counterclockwise rotation. If the direction of rotation of motor 13 is reversed, then FIG. 3 becomes an illustration of the arrested state, with magnet 31 energized to maintain the normal rest condition. If the direction of rotation is reversed, FIG. 2 becomes an illustration of the released state for the web feed device, with the current through magnet 21 momentarily interrupted to provide the requisite actuation signal.

The escapement of device 10 is bidirectional, therefore, with the following two changes required to reverse the direction of tape feed:

I-Reverse the direction of rotation of motor 13. IIChange the electrical signal input to magnet 31 to its electrical complement.

FIG. 4 illustrates the complementary nature of the electrical signals required for reversible operation of webfeed device 10'. For operation in the forward direction, as indicated by arrow A in FIG. 2, short electrical energizing signals 45 are applied to electromagnet 31. Each signal pulse 45 initiates a signal incremental advance of the paper tape or other web. The pulses need not be regularly spaced in time. They should be short enough in duration, however, to de-energize the electromagnet before armature 32 is driven back to stop 33 (from the position of FIG. 3 to that of FIG. 2) by the rotation of lever 30 effected by the ratchet wheel engaging pawl arm 28.

For operation in the reverse direction (opposite to arrow A, FIG. 2) electromagnet 31 is normally energized with a current 46 (FIG. 4) adequate to hold armature 32 in the depressed position of FIG. 3. To initiate each cycle of operation, the current 46 is interrupted briefly as shown by pulses 47 in FIG. 4. Thus, the signal pulses 47 are the complement of the signal pulses 45 used for forward movement of the web. Pulses 47 are short enough so that magnet 31 is again energized in time to bring its armature back to the position of FIG. 3 to prevent more than one cycle of web movement.

FIG. 5 illustrates a further embodiment of the invention that does not require the change in electromagnet actuating signals required for device 10. The high-speed web feeding device 50 shown in FIG. 5 is essentially similar to device (FIGS. 1-3) except that spring 29 and stop 33 are omitted and a second electromagnet 35 is added in operative relation to armature 32, magnet 35 being located above the armature. In addition, a second lever 34 is provided on the pawl member 25A; lever 34 engages the upper end of armature 32 as shown in FIGS.

With the arrangement illustrated for device 50, the electrical actuating signal requirements are simplified. A small holding current is normally maintained through both magnet 31 and magnet 35. Armature 32, therefore, remains attracted to either magnet 31 or 35, as placed. Magnets 31 and 35 are designed so that either one, when energized by a strong short pulse (e.g., one of the pulses 45, FIG. 4) will cause armature 32 to be attracted momentarily and then released as a result of the restoring force provided by ratchet wheel 21 and pawl member 25. With the arrangement shown in FIG. 5, the changes required to reverse the direction of tape feed are:

I-Reverse the direction of rotation of motor 13. 1ISupply a short operating impulse to the proper magnet, either 31 or 35.

The switching actions for both steps can be accomplished in a single simple switching device.

When both pawl arms are combined in a single pawl member, as in the devices 10 and 50, this member can be made to be symmetrical, as regards the pawl arms. As shown in FIG. 2, the two pawl arms can be mechanically identical to each other. Each pawl has a blocking surface for a given direction of rotation of the ratchet wheel; these are the surface 41 on pawl arm 26 (for clockwise rotation) and the surface 44 on pawl arm 28 (for counterclockwise rotation). Each pawl arm also has an impulse receiving surface that drives the pawl arm away from the ratchet wheel when engaged by a ratchet tooth; these are the surface 43 on pawl arm 26 (for counterclockwise rotation) and the surface 42 on pawl arm 28 (for clockwise rotation).

In this disclosure, feed roll 20 is shown driving the tape or other web 22 by friction. It is quite apparent that a sprocket wheel can be substituted for the friction wheel and the feed system may then be used to feed tape or film having sprocket holes. It is also quite evident that a pair of sprocket wheels can be employed to advance a web having two feed hole tracks, as in the case of some motion picture film. The invention may be used in a tape printer with the friction feed as shown or in a tape perforator or tape reader with a sprocket type feed wheel.

It is also apparent that two feed wheels may be spaced an appreciable distance apart to advance a sheet of paper in a typewriter, teleprinter, or accounting machine.

Although specific embodiments of the invention are shown in the drawings and described in the foregoing specification, it will be understood that the invention is not limited to those specific embodiments but is capable of modification and rearrangement and substitution of parts and elements without departing from the scope of the invention.

I claim:

1. A high-speed web feeding device for telegraph records, business machines, and similar applications requiring rapid web advancement by precisely controlled, increments, comprising:

a rotary web-feed member including a ratchet wheel having a plurality of ratchet teeth around the circumference of the Wheel;

power means, comprising a motor and a drive coupling connecting said motor to said rotary member, continuously urging said rotary member toward rotation in a given direction;

a pawl member, independent of said power means, having first and second pawl arms alternately engageable with circumferentially spaced teeth on said ratchet wheel, said first pawl arm having a tooth-engaging surface oriented to block movement of said ratchet wheel in said given direction;

actuating means for momentarily actuating said pawl member to move said first pawl arm out of engagement with said wheel and to move said second pawl arm toward engagement with said wheel to thereby initiate a web feeding movement by releasing said rotary web-feed member for rotation in said given direction in response to said power means;

and said second pawl arm having a tooth-engaging surface oriented to receive a driving impulse from one of said ratchet wheel teeth, when said rotary member rotates in said given direction, driving said second arm out of engagement with said wheel and moving said first arm back into engagement with said wheel to again block movement of said ratchet wheel.

2. A high-speed web feeding device according to claim 1 in which said power means comprises an electrical motor with a limited torque and a resilient torque-transmitting drive coupling between said motor and said rotary web-feed member.

3. A high-speed web feeding device according to claim 1 in which each of said first and second pawl arms has one tooth-engaging surface oriented to block movement of said ratchet wheel in one direction and another toothengaging surface oriented to drive that pawl arm out of engagement with said ratchet wheel in response to rotation of said ratchet wheel, the directions being opposite for said first and second pawl arms, and said power means being reversible to drive said rotary member in either direction, permitting precision incremental movement of said web in either of two opposed directions.

4. A high-speed web feeding device according to claim 3 in which said pawl member is pivotally mounted adjacent said ratchet wheel, and in which said first and second pawl arms are symmetrically oriented relative to the pivotal axis of said pawl member.

5. A high-speed web feeding device according to claim 1 in which said actuating means comprises an electromagnet having a movable armature engaged with said pawl member, said actuating means, when said electromagnet is changed between an energized and a de-energized condition, effectively moving said armature to release said first pawl arm blocking surface from engagement with said ratchet wheel and allow rotation of said rotary web-feed member.

6. A high-speed web feeding device according to claim 5, in which said power means is reversible in direction, in which each pawl arm includes both a blocking surface and a driving impulse surface, and in which energization of said electromagnet releases said first pawl arm blocking surface to permit rotation of said rotary web-feed member in one direction and de-energization of said electromagnet releases said second pawl arm blocking surface to permit rotation of said rotary web-feed member in the opposite direction.

7. A high-speed web feeding device according to claim 3 in which said actuating means comprises two electromagnets arranged to drive a single armature in opposed directions, said armature being operatively connected to said pawl member.

8. A high speed web feeding device according to claim 1 in which said power means is reversible in direction; in

References Cited UNITED STATES PATENTS 1/1906 Lorene 74-143 2/1915 Walk 64-15 8 Barber 64-15 Ewart 74-143 Hansen 74-142 Hoare 74-142 Finehout et a1. 74-142 FRED C. MATTERN, 111., Primary Examiner W. S. RATLIFF, JR., Assistant Examiner 

